1. Field of the Invention
The invention concerns adaptor systems between an antenna and a radio-frequency signal transmitter and/or receiver unit. The present invention is more specifically concerned with an adaptor system for connecting any antenna to a unit of this kind. This is a radiotelephone, for example, and one application of the present invention is to portable radiotelephones.
2. Description of the Prior Art
A portable radiotelephone is a compact unit to which an antenna for transmitting and receiving radio-frequency signals is connected. The antenna has at one end a plug cooperating with a complementary socket fixed to the unit. The plug and the socket make an electrical contact and secure the antenna mechanically to the unit and can be separated manually to remove the antenna to facilitate transporting the unit and the antenna when not in use.
A radiotelephone is designed to receive a particular type of antenna plug which means that the user is obliged to choose an antenna with a plug compatible with the socket on the radiotelephone.
Various standards cover such plugs and sockets for signal frequencies in the order of 900 MHz and SMA type connectors are usually employed. An SMA type connector comprises a female socket having a screwthread providing the ground connection and an internal conductor forming the core and a male plug comprising a nut adapted to cooperate with the aforementioned screwthread and a core. The male plug is fitted to the end of an antenna and it cooperates with the socket by screwing the nut onto the socket screwthread.
The major drawback of this type of connector is that it is not suitable for a large number of antenna maneuvers and the plug and the socket wear rapidly, leading to a deterioration in the quality of microwave transmission. Screwing one member onto the other gives rise to rubbing contact which causes the aforementioned wear. This rubbing contact occurs not only at the ground contact but also at the core and its consequence is wearing away of these contacts.
For this reason manufacturers have developed connectors which do not require one member to be screwed on to the other. One connector commonly known as a "subclic" connector is compatible with a large number of maneuvers and exploits the elasticity of a ring which is part of the antenna plug to fasten the plug to a complementary socket. The main drawback of this type of connector is its high cost and the fact that it is not in widespread use.
A major drawback of existing radiotelephones is that the user does not have a free choice from the range of commercially available antennas as the antenna must necessarily have a plug compatible with the socket on the user's radiotelephone.
An object of the present invention is to overcome these drawbacks.
A more specific first object of the invention is to provide an adaptor system between a radio-frequency signal transmitter-receiver unit and an antenna enabling the user to fit any commercially available antenna to the unit.
A second object of the invention is to provide a system of this kind allowing a large number of maneuvers to attach the antenna to the unit and detach it therefrom.
These objects and others that will emerge later are achieved by a system as defined in the next following paragraph.